Recording and monitoring optical unit



1.. T. SACHTLEBEN ETAL 2,527,454

RECORDING AND MONITORING OPTICAL UNIT Oct. 24, 1950 3 Sheets-Sheet 1 Filed May 29, 1947 M M? Z I Z 5 w Z (Ittorneg Oct. 24, 1950 L. T. SACHTLEBEN ETAL 2,527,454

RECORDING AND MONITORING OPTICAL UNIT 5 Shets-$heet 2 Filed May 29, 1947 3nnentors P ill 'IIII ulllu W! Amer/are" Z Sac/warm Gttorneg T. SACHTLEBEN ETAL 2,527,454

RECORDING AND MONITORING OPTICAL UNIT 1 3 Sheets-Sheet 3 Filed May 29, 1947 mflz #207, you 16 Mann/:-

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Gttorneg Patenteci Oct. 24, 1950 UNITED STATES PATEN T OFFICE RECORDING-AND MONITORING OPTICAL L UNIT Lawrence '1'. Sa'chtleben, Haddonfield, N. J., and James Lawrence Pettus, Sherman Oaks, Califl,

assignors to Radio Corporation of America, a 1

' corporation of Delaware H n lic tienivi jzs, 1947, Serial No. 751,406

This invention relates to sound motion picture ifilm apparatus and particularly to an optical monitoring system'for a sound film recorder whereby the. operation and adjustment of the modulating element, the condition of the light source, and the type of record beingrecorded are .indicated.

Monitoring systemswhich utilize a beam of light vibrated by a modulating element, such as the mirror of a galvanometer', and projected to an observation medium to indicate'the adjust- .ment and operation of the modulating element, as well as the condition of the light source; have been used. 7 Monitoring systems which show, the typeof record being recorded are also known.

. For instance, Dimmick v co-pending 'application, Ser. No. 629,295, filed November 17, 1946, now

Patent No. 2,468,( J48, shows a characterized type of monitoring system, while S'achtleb'en andPettus co-pending application, Ser. No. 743,620; filed April 24, 1947, now Patent No. 2,504,591 shows a unitary type of recording and monitoring system of the general formof the present invention,

The monitoring. system disclosed hereinafter,

: however, not only combines the features of various prior systems, but alsohas simplified the con: str1 1ction and positioning of the optical units to provide a particularly compact, efiici'ent and eco nomical structure. Practically all of the'advantages of the more expensive and complicated systems are obtained while reducing the number of v optical elements and their adjustments. Therefore, there is less likelihood of the system becoming misaligned during operation.

The principal object of the invention, therefore, is to facilitate the recording of a sound recaord and the monitoring of the modulating element and light source employed in the recording operation.

Another object of the invention is to provide an improved method of and system for obtaining an indication of the operation and adjustment of.

a sound recording modulating element and the 1 condition of the light source ofthe recording system.

A further object of the invention is to provide an improved and simplified monitoring optical J system for photographic sound recorders;

"A still further object of the invention is to iZpTOVide an improved monitoring system which :'.indicates the operation and adjustment of the. modulating elements, the condition of the light source and thejtype of record being recorded.

i" PIA still further object of the invention'is to I provide a monitoring optical unit in; integral 'zassociation;withcits recordinggoptica-l unit 8 Claims. (Cl. 179-1003) I plate.

Although the novel features which are believed to be characteristic of this invention will be Fig. 3 is a front view of the unit of Fig. 1, par- .tially in cross-section; l5

r Fig. 4 is a detailed view, partially in crossse'ctionjof the unitary optical element for'the light source takenalong the line 44 of Fig. 2;

Fig. 5 is a cross-sectional view of the aperture and recording optical unit between the light sourceand modulator taken along the line 5-5 of Fig. 2; V

Fig. 6 is a perspective view of one of the optical I elements of the monitoring system for the modu lator Fig. '7 is a perspective view of another'optical element of the monitoring system for the modulator 1 v Fig. 8 is a diagrammatic perspective view of the optical elements of the recorder and monitoring system;

Figs. 9 and 10 are views of the observation screen showing two positions of adjustment of the modulator; a a

Fig. 11 is a front view of the one form of recording aperture; and; v

Fig. 12 is a front view of the reordngslit I Referring now to the drawings in whichflike "numerals identify'identical elements and par- 40 ticularly to Fig.8, a light source 5 having afila- 'ment 6 provides light for the. recording andfmonitoring systems, the light gathered by condenser lenses' 8,;being projected through a recording apf'erturefifand monitoring apertures 10 and [I of these apertures is projected to the mirror I5fof an .aperture plate. [3. The emergent lig'ht from agalvanometer modulator through an intermediate lens l6,.t he light beingrefiected by the mirror l5. to a condenser lens l8. andthen to a slit plate l9 having slits 20, 2! and 22 therein. Emergent lightfrom; the slits is impressed upona film 25by an objective lens unit 26, thelightjpassing through a filter,-2"l if desired. The mainrecording-ray is shown by the broken line 2-9. The

above described optical system is of the type dis- .Ql g and cla med; n i k fi d ng?!- 3 plication, Ser. No. 742,545, filed April 19, 1947, now Patent No. 2,468,049.

The monitoring optical portion of the system utilizes the light rays passing through apertures l6 and H; indicated by the broken lines 3| and 32, the rays 3| and 32 being shown as a single line 33 beyond the mirror i5 for the sake of clarity. The light rays 3| and 32 are received upon a lens mirror 35 which is a plano convex lens a plane mirror 38 and then parallel to the axis of lens (8 to a plane mirror 39 which directs the .light forward to the back of a translucent screen 40 as indicated by an image ll and one of the images 44 or 45, as will be explained hereinafter. The vibrations of the galvanometer mirror l5 about its axis in the horizontal plane causes the monitor image M to move in a vertical direction and in a plane very near the lens mirror 35. This image is then formed on the monitor screen by .lens 31 at a magnification of about five times and where it moves in a vertical direction.

For monitoring the filament 6 of the lamp 5,

ligbt coincident with the recording axis 29 is reflected upwardly by a prism 41 through a spherical lens 48 to a mirror 43 which projects the light forward to the screen 46 as shown by an image 5|.

To illustrate the action of the monitoring system, reference is made to Figs. 9 to 12, inclusive, wherein front views of the aperture plate 1 l3 and slit plate I9 are shown, as well as the images on the screen 46, when recording different types of records such as a negative and a direct positive. The aperture plate l3 has a W-shaped aperture 9 therein and two monitoring apertures l9 and H, the latter two being off-set substantially one-half the width of each aperture. When the galvanometer is tilted so that light along the upper side edge of aperture 9 lies along the slit 26, a negative record will be obtained upon normal development of the film, and the light through aperture will appear as a shaded image such as shown at 52 in Fig. 9.

When the galvanometer mirror is adjusted so that the light through the lower side edge of I the aperture 9 lies along the slit 29, a direct positive record will be obtained upon normal development of the film, and the light through aperture II will form a shaded image such as shown at 53 in Fig. 10. The dotted lines 55 in Fig. 9 show the position of the direct positive monitoring image in Fig. 10, while the dotted lines 56 in Fig. 10 show the position of'the negative monitoring image in Fig. 9 for the purpose of comparison. The images 52 and 53 vibrate in a vertical direction in accordance with the amplitude of the signal being recorded, 100% modulation being indicated by the upper lines 58. As the amplitude of the signal increases, the application of noise reduction bias is indicated by the position of the lower edge of the beam, 100% bias being shown by lines 6|]. The filament image is, of course, shown in each instance.

It will be noted in Fig. 9, that when the system is adjusted for recording a negative record, an upper square 62 is illuminated. This square may be marked with a letter N to indicate that a negative record is being recorded. In Fig. 10, a lower square 63 is shown having the letter P marked therein to indicate that a direct positive record is being recorded. Respective squares 62 and 63 are illuminated by light passing through the other aperture not being used to produce images 52 and 53. That is, the light passing through aperture i0 produces image 52 when a negative record is being recorded, while light passing through aperture ll produces the image 62 to illuminate the letter N Similarly, when a direct positive record is being recorded, light through aperture I l produces the image 53, while light through aperture I6 produces the image at 63 to illuminate the letter P. Thus, not only is the modulating images 52 and 53 shown together with filament image 5|, but also an indication is obtained of the type of record being recorded.

To illustrate the dimensions involved in a practical system, such as described above, the distance from the filament 6 to the mirror l5 was 5.135 inches while the distance from the mirror [5 to the film 25 was 9.070 inches for recording on 35 mm. film. The distance from the mirror l5 to the slit plate l9 was 2.6305 inches and the distance from the lens mirror 35 to the slit plate l9 was .298 inch. The distance between lens mirror 35 and mirror 36 was .9375 inch. The vertical distance from mirror 36 to mirror 38 was 2.234 inches While the lens 31 was positioned .166 inch above the lens 36. The mirror 39 was positioned 2.3125 inches from the mirror 38 while the distance between the screen 40 and. the mirror 39 was .375 inch. With respect to the elements 41, 48 and 49 for monitoring the filament 6, the distance between the filament and the prism 41 was 1.375 inches while the vertical distance was 2.687 inches and the distance between the mirror49 and the screen 40 was 4.103 inches. These dimensions provided a compact and unitary optical arrangement, the images on the screen 40 being particularly stable and sharp.

To illustrate the structures and mountings of the various optical elements just described, reference is made to Figs. 1 to '7, inclusive. All optical elements are mounted on a plate 65 having elongated holes 66 therein to permit adjustment of the base with respect to the film 25. A fine lateral adjustment of the optical axis 29 is obtained by a pair of set-screws 61.

The lamp 5 is in a mount H4 attached to the base 65 and has an automatic release lever 69 such as disclosed and claimed in Pettus copending application Ser. 739,007, filed April 2, 1947. A cylindrical casing on barrel 1| contains the aperture plate l3 and lenses 8, the casing being mounted in an opening in a Wall section 12 of the base 65. The lenses 8 and slit plate l3 are held in a sleeve holder 16 which may be doweled to the casing 11 by a dowel 15 to fix the position of the plate and lenses in the barrel 1|. The barrel 1| has a key 11 in a groove in the casting 12, the key being attached to the upper surface of the barrel by a screw 18 and a dowel 19 to properly orient the aperture 9. The

- entire unit is then adjusted longitudinally and held in the wall section 12 by a screw 80.

The galvanometer 82 is mounted in a bracket 83 on a horizontal pivot formed by screws 84 and 85. Lateral adjustment of the galvanometer 5;. may be. obtained,=.by adjustment .of screws. 86 and 81, while the-.galvanometer may be vtilted'on its horizontal axis by a thumb screw 88 bearing against the lower edge of the galvanometer. When the screw 88 is backed off aspring 89 tilts the galvanometer in the opposite direction.

The net unit is a housing 90 having a cylindrical barrel III at the front end thereof which houses the condenser lens I8 and the slit plate I9, (see Fig. 3) and the .projection optical unit 26 at the other end thereof. Within the housing 90 may also be positioned a shutter and a filter 21 as described in the above identified co-pending application of Sachtleben and Pettus.

The above described unit performs the recording operation utilizing the light as indicated by ray 29 in Fig. 8. The monitoring units include elements I shown in Fig. 4, IOI shown in Fig. 6, I02 shown in Fig. 7, and I03 shown in Fig. 3. The elements IN and I02 are mounted on part of the casting of the housing 90 as shown at I05. The post I06 is set into the casting I and held therein by a set-screw I01, the end of which sets in the notch I08 of the post. The upper portion of the post I06 is flattened and the lens mirror 35 is cemented on the flat surface of the post. The long back flat surface is desired to permit the removal of the post I06 past the lens barrel 9 I. At the other end of the casting I05 is a second post IIO having a notch II2 therein which accommodates the end of a set-screw II 3 for holding the post in position. The top of the post IIO supports the mirror 36 on an angular side of the notch in a block I20 therein, while the upper extension of the block supports the lens 31. The posts I06 and H0 are adjusted so that the light beam 33 is reflected by the lens mirror 35 to the mirror 36.

Mounted on the upper surface of housing 90 by screws such as shown at H5 in Fig. 2 is a rectangular shaped casting having a triangular closed end II8, the bottom portion of the triangular end II8 having an opening II9 through which the light from the lens 31 passes to the mirror 38 cemented on the angular side of the end '8. On a rear angular vertical side of the casting N1 the mirror 39 is cemented which reflects the light forwardly to the translucent glass plate 40 which is held in position by a cover I2I fastened to the casting by screws such as shown at I22. The light path thus provided by the elements I 0|, I02 and I03 positions the images shown in Figs. 9 and except forthe filament image 5I, which is received through the open back portion of the casting I I1.

Referring now to Figs. 1, 2 and 4, there is mounted on the base II4 of the lamp 5 a rod I25 supporting a tube I26, in the base of which is mounted the prism 41 and lens 48 on a block I21. The prism and lens are held by a clip I28 attached to the block I21 by a screw I29, the entire assembly being held in position by a set screw I3I. Light from the filament 6 reaches the prism 41 through a hole I32 in the tube I26, the light being reflected upwardly to the mirror 49 attached to a plug I34 held in position by a set-screw I35. The light reaching the mirror 40 is reflected from the tube I26 through an opening I31 therein to the screen 40 to form the image 5! of the filament 6. The images 4|, 44, 45 and 5| are thus viewed from the front side of the screen 40 in a plane along the front portion of the optical unit.

It is to be noted that the monitoring optics for the modulator 82 have been simplified to a minimumby utilizing only units I 0| I02 and I03, the element I03 also providing the image of. the filament in association with the unit I00. The. lamp filament optics are all contained in a single unit which may be quickly attached to and detached from the recorder optical unit as shown in Fig. 4. Adjustments may thus be made on a. bench away from the recorder. The-modulator monitoringoptics are also contained in the minimum of units which, when fixed in posi tion, are dimcult to get out ofv alignment, but very easily adjustable if they do. The monitoring images are presented in a manner to permit easy daylight observation thereof, and are presented in a position to be easily observed. The various units are easily accessible for cleaning, removal or repair, While all adjustments, as mentioned above, may be made with the entire unit on a bench before attachment to the recorder.

Although this invention has been illustrated for recording a certain type of record, it is to be understood that it may be used'for recording other types of records by changes inthe shape of the aperture 9. Furthermore, it is adaptable to the recording of sound tracks on either 35 mm. or 16 mm. film.

1 We claim:

1. The method of simultaneously indicating the adjustment and operation of a sound recording modulating element adapted to record either a negative record or a direct positive record on a film, comprising forming light into a plurality of light beams, one of said beams being of a chevron-shaped type in which the projection of a certain portion of light from one edge of said beam forms a negative record, and light from another edge of said beam forms a direct positive record, vibrating said beams in accordance with sound waves to be recorded, projecting light from said other beams for observation, utilizing one of said other beams for indicating the amplitude of vibration of said chevron-shaped beam, and utilizing another of said other beams for indicating the certain portion of said chevron-shaped beam being projected to the film.

2. The method in accordance with claim 1, which includes forming another light beam and projecting said other beam for observation to indicate the condition and adjustment of the light source for generating said beams.

3. The method of simultaneously indicating the adjustment and operation of a sound recording modulating element adapted to record either a negative record or a direct positive record on a film, comprising forming light into three beams, one of said beams being of a chevron type, whereby the projection of the varying section of one edge of said beam forms a negative record, and the projection of the varying section of the other edge of said beam forms a direct positive record, vibrating all of said beams in accordance with sound waves to be recorded, projecting the other two beams for observation utilizing one of said other beams for indicating the amplitude of vibration of all of said beams, and utilizing the third beam for indicating the particular varying section of said chevron type beam being projected to the film.

4. The method in accordance with claim 3, which includes utilizing said one other beam for indicating amplitude, when said third beam indicates the particular varying projected section of said first mentioned type beam, and utilizing said third beam for indicating the amplitude when said one other beam indicates the particular projected varying section of said first mentioned type beam.

5. A monitoring system for a recording system, comprising :a recording optical path including a light source, a light beam modulator, a slit, and a projector unit, and a monitoring optical path including two vertically fixed posts, one of said posts having a reflector at one end thereof for reflecting light from said modulator, the other of said posts having a reflector and a lens at one end thereof for reflecting and projecting said light for observation, and a vertical tube having a reflector and lens in one end thereof and a reflector in the other end thereof for reflecting and projecting light from said source for observation.

6. A monitoring system in accordance with claim 5, in which a casting having a rectangular section and a triangular section is mounted above said projector unit, said triangular section containing a reflector for light from said second mentioned post, and said rectangular section being open on one side to receive light from said tube.

7. A monitoring system for a photographic sound recording system, comprising a base, a light source, a light beam forming unit, a light beam modulator, and a light beam projector unit adjustably mounted on said base, a Pair of rodlike adjustable supports between said light beam modulator and said projector unit, optical elements on the ends of said supports for reflecting and projecting light from said modulator rear- 8; wardly andzupwardl'y, cacasting mounted on said projector unit, a screen in said casting, and op-v tical'el'ements in said casting for reflecting light from said.- optical elements on said supports to said screen. 1

8. A monitoring system in accordance with claim 7, in which a vertical tube is mounted adjacent said light source, optical elements in said tube for receiving light from said source, reflecting said light upwardly, and projecting said light horizontally to said screen through an opening in the rear of said casting.

- LAWRENCE T. SACHTLEBEN. JAMES LAWRENCE PETTUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,955,378 Dimmick Apr. 17, 1934 2,166,186 Stack July 18, 1939 2,220,198 Batsel Nov. 5, 1940 2,233,907 Zimmerman Mar. 4, 1941 2,233,914 Collins Mar. 4, 1941 2,238,291 Runge Apr. 15, 1941 2,270,350 schomacker Jan. 20, 1942 2,468,047 Dimmick Apr. 26, 1949 2,468,049 Dimmick Apr. 26, 1949 2,468,142 Ulmer Apr. 26, 1949 

